The long range goal of this proposal is to understand the mechanism of catabolite repression which effects and controls carbohydrate utilization in Streptococcus mu tans and how this process is involved in the pathogenesis of S. mutans-induced dental caries. The mechanism of catabolite repression is not understood in Gram positive bacteria and elucidation of this process will potentially allow better prevention of dental caries. However, this long range goal can not be achieved without first attaining a basic understanding of the local regulation of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) Of carbohydrate transport in S. mutans. Therefore, the short term goal of this proposal is to initiate studies into the regulation of the S. mutans PTS. The individual specific aims of this proposal include: 1.) isolation and cloning in E. coli K12 of S. mutans gene clusters involved in the transport and utilization of various carbohydrates via the PTS; 2.) identification of the gene products of the isolated PTS gene clusters by in vitro gene expression systems; 3.) determination of the nucleotide sequences of the isolated PTS gene clusters to determine the overall operon structures, to identify regions for the in vitro generation of transcriptional and translational fusions, and to identify putative regulatory control regions; 4.) in vitro generation of transcriptional fusions to monitor regulation of the S. mutans PTS in response to various carbohydrates; 5.) analysis of the putative promoter regions of the isolated PTS gene clusters and identification and analysis of putative control regions involved with regulation of these operons using translational fusions; and 6.) assay of transcriptional activity of the S. mutans PTS catabolic enzyme genes under various environmental conditions. Accomplishment of these specific aims will provide the necessary information to initiate studies into the long range goal and will be paramount to understanding carbohydrate utilization and regulation of this process in Streptococcus mutans.